--- include/winnt.h	(revision 3516)
+++ include/winnt.h	(revision 3517)
@@ -3121,7 +3121,7 @@
       __MINGW_EXTENSION union {
 	PVOID FiberData;
 	DWORD Version;
-      } DUMMYUNIONNAME;
+      };
       PVOID ArbitraryUserPointer;
       struct _NT_TIB *Self;
     } NT_TIB;